A preferred embodiment of the invention is directed to reducing fouling in Coking Processes.
Fluidized bed coking (fluid coking) and FLEXICOKING are petroleum refining processes in which mixtures of heavy petroleum fractions, typically the non-distillable residue (resid) from fractionation, are converted to lighter, more useful products by thermal decomposition (coking) at elevated reaction temperatures, typically about 900 to 1100xc2x0 F. (about 480 to 590xc2x0 C.) by heat supplied by fluidized coke particles.
Fouling in the stripper and scrubber sections of a Coker vessel results in decreased capacity and run length of the unit, culminating in costly unplanned shutdowns.
Fluid Catalytic Cracking (FCC) is another petroleum refining conversion process in which heavy oil, typically the highest boiling distillable fraction, is converted to gasoline, diesel and jet fuel, heating oil, liquefied petroleum gas (LPG), chemical feedstocks, and refinery fuel gas by catalytic decomposition at similarly elevated temperatures of about 900 to 1100xc2x0 F. (about 480 to 590xc2x0 C.). Run length or capacity of an FCCU may likewise be limited by deposition of coke in the stripper, reactor overhead, plenum, nozzle, transfer line, or inlet to the fractionator.
What is needed in the art is an efficient, predictable, and effective way to mitigate the fouling tendency in the stripper, scrubber, surge drum and other sections of coking units.
An aspect of the invention is directed to a process for decreasing fouling in refinery unit reactor zones wherein said refinery unit reactor zone is run at temperatures of at least about 300xc2x0 C. and wherein said feed experiences heating in said refinery unit reaction zone, comprising pre-heating the feed to said refinery unit reactor zone and thereafter introducing said feed into said refinery unit reactor zone for reaction, wherein said feed contains polymers and oligomers, and wherein said feed is pre-heated for a time and at a temperature sufficient such that when said feed is introduced into said refinery unit reaction zone for reaction, the combination of said pre-heating and heating attributable to said reaction zone causes at least 85% of said polymers and oligomers contained in said feed to unzip and wherein no more that about 5 wt % coke is formed in said feed during said heating.
The invention is particularly useful in coking and cracking refinery units.